System and method for conditioning a fluid using bleed air from a bypass duct of a turbofan engine

ABSTRACT

Systems and methods for conditioning a fluid using bleed air from a bypass duct of a turbofan engine are disclosed. The system comprises a heat exchanger configured to facilitate heat transfer between a flow of bleed air from the bypass duct of the turbofan engine and the fluid, and a fluid propeller configured to drive the bleed air through the heat exchanger. The fluid propeller is disposed downstream of the heat exchanger.

FIELD

This relates to aircraft engines and, more particularly, to using bleedair from an aircraft engine to condition a fluid.

BACKGROUND

Turbofan gas turbine engines generally include a bypass air duct thatdirects a bypass air flow drawn by a fan. The bypass air duct surroundsan engine core including a compressor section, a combustor, and aturbine section. An opening in a wall of the bypass air ductcommunicates with a bleed pipe such that bleed air may be directed fromthe bypass air duct to a heat exchanger or pre-cooler via the bleedpipe. The pre-cooler can use the bypass air to cool a supply fluid suchas pressurized air to an environmental control system or an ice controlsystem of an aircraft for example. Such pre-coolers are typically sizedto accommodate a maximum expected load and are housed in a pylon of anaircraft. The size of the pre-cooler can partially dictate a requiredsize of the pylon.

SUMMARY

According to an aspect, there is provided a system for conditioning afluid using bleed air from a bypass duct of a turbofan engine. Thesystem comprises:

a heat exchanger configured to facilitate heat transfer between a flowof bleed air from the bypass duct of the turbofan engine and the fluid;and

a fluid propeller configured to drive the bleed air through the heatexchanger, the fluid propeller disposed downstream of the heatexchanger.

According to another aspect, there is provided a system for conditioningsupply air for an environmental control system of an aircraft. Thesystem comprises:

a turbofan gas turbine engine having a bypass duct;

a heat exchanger configured to facilitate heat transfer between a flowof bleed air from the bypass duct and the supply air; and

a fluid propeller configured to drive the bleed air through the heatexchanger, the fluid propeller disposed downstream of the heatexchanger.

According to another aspect, there is provided a method for conditioninga fluid using a flow of bleed air from a bypass duct of a turbofanengine. The method comprises:

at a heat transfer location, transferring heat between the fluid and theflow of bleed air from the bypass duct of the turbofan engine; and

driving the flow of bleed air through the heat transfer location, alocation of the driving being downstream of the heat transfer location.

Other features will become apparent from the drawings in conjunctionwith the following description.

BRIEF DESCRIPTION OF DRAWINGS

In the figures which illustrate example embodiments,

FIG. 1 is a partial schematic cross-sectional view of a gas turbineengine, in accordance with an embodiment;

FIG. 2A is a schematic cross-section view of a gas turbine engine with afluid conditioning system having an auxiliary compressor upstream of apre-cooler, in accordance with an embodiment;

FIG. 2B is a schematic cross-section view of a gas turbine engine with afluid conditioning system having an auxiliary compressor downstream of apre-cooler, in accordance with an embodiment;

FIG. 2C is a flow diagram of an example method for conditioning a fluidusing a bleed air flow augmented by an auxiliary compressor, inaccordance with an embodiment;

FIG. 3A is a schematic cross-section view of a gas turbine engine with afluid conditioning system having a fluid-driven auxiliary compressorupstream of a pre-cooler, in accordance with an embodiment;

FIG. 3B is a schematic cross-section view of a gas turbine engine with afluid conditioning system having a fluid-driven auxiliary compressordownstream of a pre-cooler, in accordance with an embodiment;

FIG. 3C is a schematic of a fluid-driven auxiliary compressor, inaccordance with an embodiment;

FIG. 3D is a schematic of a fluid-driven auxiliary compressor with aninternal turbine, in accordance with an embodiment;

FIG. 3E is a flow diagram of an example method for conditioning a fluidusing a bleed air flow augmented by a fluid-driven auxiliary compressor,in accordance with an embodiment;

FIG. 4A is a schematic of a fluid conditioning system having an ejectorpump, in accordance with an embodiment;

FIG. 4B is a flow diagram of an example method for conditioning a fluidusing a bleed air flow augmented by an ejector pump, in accordance withan embodiment;

FIG. 5A is a schematic of a fluid conditioning system having amechanically-driven auxiliary compressor, in accordance with anembodiment;

FIG. 5B is a flow diagram of an example method for conditioning a fluidusing a bleed air flow augmented by a mechanically-driven auxiliarycompressor, in accordance with an embodiment;

FIG. 6A is a schematic of a fluid conditioning system having anauxiliary compressor and an ejector pump, in accordance with anembodiment; and

FIG. 6B is a flow diagram of an example method for conditioning a fluidusing a bleed air flow augmented by an auxiliary compressor and anejector pump, in accordance with an embodiment.

DETAILED DESCRIPTION

Pre-coolers used to cool air for aircraft systems, such as customerenvironmental control system (ECS) air, are designed and sized based onair properties provided by an engine supplier. As such, a pre-cooler issized to fit a particular engine and designed to fit within a volume ofthe pylon of that engine. Bleed air flow from a bypass duct flow drawnfrom the engine fan may form a cooling flow for the pre-cooler.

However, aircraft design may change. In an example, the engine may bechanged, and thus the pressure of the cooling flow supplied to thepre-cooler may be modified or reduced as compared to the initial engine.Typically, a solution to address a reduced pressure of cooling flowwould be a re-design of the pre-cooler, as the lack of supply pressurefrom the bleed air flow means that the pre-cooler passages would need tobe increased in order to provide adequate cooling flow to thepre-cooler. Increasing pre-cooler capacity can mean that the pre-coolersize would need to increase and, as a result, pylon design would need tobe changed.

In the event the aircraft nacelle and pre-cooler have already passedthrough a design stage, a re-design of the nacelle and pre-cooler may becostly in time (for e.g., affecting aircraft delivery schedule), money,and aircraft performance (for e.g., a larger nacelle and/or pylon neededto fit a bigger pre-cooler may affect performance of the aircraft). Anincrease to nacelle or pylon size can result in aircraft fuel penaltyduring forward flight conditions, due to aerodynamic drag, thusaffecting aircraft performance.

In embodiments disclosed herein, a fluid propeller, such as an auxiliarycompressor and/or an ejector pump, may be used to increase the flow rateof bleed air flow as cooling air for a pre-cooler, for example, byincreasing the pressure gradient or pressure differential across thepre-cooler. Such fluid propeller may be electrically or mechanicallydriven.

The use of the fluid propeller may allow for an otherwise undersizedpre-cooler to be used since the fluid propeller can increase the flow ofcooling air through the pre-cooler when needed. A smaller pre-cooler mayallow for a smaller pylon size and therefore less aerodynamic drag.

A fluid propeller as described herein may be activated in conditionswhen additional cooling air flow is needed, which may be infrequent.Such conditions may include high air demand conditions while the engineis operating at a relatively low power, in an example, the demands of ananti-ice system while an aircraft is cruising at 15,000-20,000 feet in aholding condition.

A fluid propeller as described herein may be activated such that theadditional power extraction required to drive the fluid propeller onlyaffects thrust-specific fuel consumption (TFSC) at non-critical specificfuel consumption (SFC) conditions.

Thus, using techniques described herein, the flow rate of cooling airsupplied to a pre-cooler may be increased without increasing nacelle orpylon size and the cooling air can sufficiently cool pressurized air forcirculation to an aircraft system.

FIG. 1 illustrates a turbofan gas turbine engine 10 of a type providedfor use in subsonic flight, generally comprising in serial flowcommunication along a centerline 11: a fan 12 through which ambient airis propelled, a compressor section 14 for pressurizing the air, acombustor 16 in which the compressed air is mixed with fuel and ignitedfor generating an annular stream of hot combustion gases, and a turbinesection 18 for extracting energy from the combustion gases. Thecompressor section 14 and the turbine section 18 form part of an enginecore 20. The engine core 20 defines a main fluid path 22 in which thecombustor 16 is provided. The engine core 20 is coaxially positionedwithin an annular bypass duct 24 including an annular radially outerbypass duct wall 26 and an annular radially inner bypass duct wall 28.The radially outer and inner bypass duct walls 26 and 28 definetherebetween an annular bypass air passage 30 for directing a bypass airflow 32 drawn by the fan 12.

FIG. 2A illustrates an example of a gas turbine engine system, includingengine 10 and a fluid conditioning system 200 having a fluid propeller,such as an auxiliary compressor 208, configured to drive bleed air flow210 through pre-cooler 206. In the embodiment illustrated in FIG. 2A,auxiliary compressor 208 is disposed upstream of a pre-cooler 206. Insome embodiments, auxiliary compressor 208 is disposed downstream ofpre-cooler 206, for example, as shown in FIG. 2B.

Fluid conditioning system 200 is operable, among other things, tocondition a supply fluid such as a pressurized air flow 201A drawn fromengine core 20, in an example, from compressor section 14, for coolingby a heat exchanger such as a pre-cooler 206 using bleed air flow 210bled from bypass duct 24, and forming a cooled pressurized air flow 201Bfor use in aircraft air systems, such as an environment control system(ECS) 40, an anti-ice system or secondary air systems of engine 10.

In the embodiment of engine 10 illustrated in FIG. 2A, compressorsection 14 includes a low pressure compressor (LPC) 15A forming a streamfor further compression by high pressure compressor (HPC) 15B to formfurther compressed air fed to combustor 16.

Turbine section 18 of engine 10 illustrated in FIG. 2A is a three-stageturbine, including a single-stage high pressure turbine (HPT) 19A and atwo-stage power or low pressure turbine (LPT) 19B, for extracting energyfrom the combustion gases of engine 10. In other embodiments, turbinesection 18 may be another suitable single stage or multi-stage turbine.

In some embodiments, a power shaft 50 and an engine core shaft 52 ofengine 10 may be mechanically uncoupled, for example, in a dual spoolconfiguration having a low-pressure spool and a high-pressure spool,respectively, and therefore may permit separate rotation. Thus, HPC 15Band HPT 19A may be mechanically uncoupled from LPC 15A and LPT 19B, andtherefore may permit separate rotation.

Engine 10 may have a dual-spool configuration as described herein, butit is understood that engine 10 may not be limited to suchconfiguration.

While FIG. 2A illustrates a gas turbine engine system including aturbofan gas turbine engine, any other suitable engine may be employed.

Fluid conditioning system 200 includes a bleed air conduit such as bleedpipe 202 having an inlet end 203 connected to one of outer bypass ductwall 26 or inner bypass duct wall 28 of bypass duct 24. In theembodiment of FIG. 2A, inlet end 203 of bleed pipe 202 is connected toouter bypass duct wall 26 of bypass duct 24 such that an opening 204 inouter bypass duct wall 26 of bypass duct 24 is aligned with acorresponding opening at inlet end 203 of bleed pipe 202.

Bleed pipe 202 is thus connected in fluid flow communication with bypassduct 24, such that bypass air flow 32 flowing within bypass duct 24 canbe extracted from bypass duct 24 and into bleed pipe 202, via opening204.

Bleed pipe 202 may extend perpendicularly from bypass duct 24, or atanother suitable angle.

Bleed pipe 202 and opening 204 may be sized to admit a desired quantityof air, for example, to provide cooling air to pre-cooler 206, asdiscussed in further detail below.

Bleed pipe 202 defines a bleed fluid path 211 through which bleed airflow 210 flows, cools pre-cooler 206 as a cooling flow, and is exhaustedto bleed exhaust 220, as described in further detail below.

Fluid conditioning system 200 also includes an air pathway or conduitestablishing fluid communication between pre-cooler 206 and engine core20 for directing pressurized air flow 201A from engine core 20 topre-cooler 206.

In some embodiments, pressurized air flow 201A is drawn from a locationdownstream a low pressure compressor, such as LPC 15A, of engine core20. In some embodiments, pressurized air flow 201A is drawn from alocation downstream a high pressure compressor, such as HPC 15B, of theengine core 20.

In an example, pressurized air flow 201A may be drawn from HPC 15B ofcompressor section 14, such as compressor discharge air pressure (P3).In some embodiments, pressurized air flow 201A may be drawn from othersuitable sections of compressor section 14 or other parts of engine core20, such as between LPC 15A and HPC 15B.

Pressurized air flow 201A may be a relatively high pressure flow, andhigher pressure than bleed air flow 210 within bleed pipe 202.

Pre-cooler 206 operates as a heat exchanger configured to facilitateheat transfer between a fluid, such as pressurized air flow 201A that iscirculated in pre-cooler 206, and bleed air flow 210, to form cooledpressurized air flow 201B for use in aircraft air systems, such as anenvironment control system (ECS) 40.

Pre-cooler 206 is in fluid communication with bleed fluid path 211,which supplies air flow, such as bleed air flow 210, to cool pre-cooler206.

In some embodiments, pre-cooler 206 has a body in which passages aredefined, through which pressurized air flow 201A flows. The passagesdefine heat exchange surfaces exposed to bleed fluid path 211 in bleedpipe 202.

Pre-cooler 206 may include projections of the passages that project intobleed fluid path 211, further defining heat exchange surfaces. Forexample, fins may project outwardly or inwardly, be radially orquasi-radially oriented, and may extend in a generally axial directionwith reference to the direction of bleed air flow 210.

Pressurized air flow 201A is circulated in pre-cooler 206 by way of thepassages, and air circulating in bleed pipe 202, such as bleed air flow210, may circulate through the channels defined between the passagesthrough which pressurized air flow 201A flows. Pressurized air flow 201Ais thus placed in thermal exchange contact with a flow of cooling air,namely bleed air flow 210, coming from bleed fluid path 211.

It should be understood that other heat exchanger configurations forfacilitating heat transfer between fluid streams can be suitable forpre-cooler 206.

In an example scenario, such as during an aircraft idle or descent atwhich point engine 10 is operating at a low power rating, pressurizedair flow 201A may be at a lower pressure. In such scenarios, air flowfor various systems may not require pre-cooling, and thus pre-cooler 206may be bypassed which may avoid a loss of pressure of pressurized airflow 201A by pre-cooler 206.

Auxiliary compressor 208, an example fluid propeller, may increase flowrate of bleed air flow 210 through pre-cooler 206 by pushing air throughpre-cooler 206 when disposed upstream pre-cooler 206, or by pulling airthrough pre-cooler 206 when disposed downstream pre-cooler 206.

Auxiliary compressor 208 may operate as a pressure augmenting device.For example, auxiliary compressor 208 disposed upstream of pre-cooler206 (in the direction of bleed air flow 210) may increase staticpressure upstream of pre-cooler 206. Auxiliary compressor 208 disposeddownstream of pre-cooler 206 (in the direction of bleed air flow 210)may decrease static pressure downstream of pre-cooler 206 by generatinga pressure drop immediately upstream auxiliary compressor 208. Thus, thepressure gradient or differential (in particular, a pressure drop)across pre-cooler 206 may be increased, and the flow rate of bleed airflow 210 through pre-cooler 206 increases.

Auxiliary compressor 208 may include a rotatable fan that rotates aboutan axis of rotation that is generally parallel to bleed air flow 210 toincrease the flow of air in bleed fluid path 211.

In some embodiments, auxiliary compressor 208 is an axial compressorhaving one or more stages. In some embodiments, auxiliary compressor 208is an axial compressor having multiple stages of alternating rotatingand stationary airfoils, such that in operation, a given stage ofrotating airfoils accelerate fluid flow (such as bleed air flow 210) inaxial and circumferential directions and stationary airfoils convert theincreased kinetic energy into static pressure through diffusion andredirect the flow to a next stage.

In some embodiments, auxiliary compressor 208 is a centrifugalcompressor that adds kinetic energy to a fluid flow (such as bleed airflow 210) through an impeller, and the kinetic energy is then convertedto increase static pressure by slowing the flow through a diffuser.

In some embodiments, auxiliary compressor 208 is powered electricallywith power to an electrical motor or by way of an electric generator(not shown) driven by engine 10 or by way of some other suitableelectric source (e.g., battery).

In some embodiments, auxiliary compressor 208 is powered mechanically.In an example, auxiliary compressor 208 may be fluid-driven, such asdriven by a flow of pressurized air. In another example, auxiliarycompressor 208 may be drivingly coupled to an accessory gearbox (AGB)driven by a power shaft, for example, power shaft 50, connected to anddriven by one or more turbines of turbine section 18. In a furtherexample, auxiliary compressor 208 may be driven by a compressor shaft ofengine 10.

As shown in FIG. 2A, with auxiliary compressor 208 upstream ofpre-cooler 206, bleed air flow 210 is compressed by auxiliary compressor208, increasing pressure in bleed fluid path 211 and thereby increasingthe flow of bypass air flow 210 supplied to cool pre-cooler 206 which isthen exhausted to bleed exhaust 220, for example, dumped into an exhauststream fed into a pylon section of the aircraft which then exitsoverboard at a rear of the pylon.

Auxiliary compressor 208 may be operatively disposed upstream ofpre-cooler 206, as shown by way of example in FIG. 2A, or downstream ofpre-cooler 206, as shown by way of example in FIG. 2B.

As shown in FIG. 2B, with auxiliary compressor 208 downstream ofpre-cooler 206, bleed air flow 210 travels as a cooling flow throughpre-cooler 206 before reaching auxiliary compressor 208 which increasesthe flow rate of bleed air flow 210 through pre-cooler 206. Bleed airflow 210 is then exhausted to bleed exhaust 220, for example, dumpedinto an exhaust stream fed into a pylon section of the aircraft andexited overboard at a rear of the pylon.

Conveniently, auxiliary compressor 208 disposed downstream of pre-cooler206 may have the benefit of not further raising the temperature of bleedair flow 210 prior to entry into pre-cooler 206 for cooling pressurizedair flow 201A.

In some embodiments, a first fluid propeller, such as auxiliarycompressor 208, is disposed downstream of a heat exchanger such aspre-cooler 206, and a second fluid propeller, such as auxiliarycompressor 208, is disposed upstream of a heat exchanger such aspre-cooler 206.

FIG. 2C is a flow diagram of an example method 260 for conditioning afluid, such as pressurized air flow 201A, using bleed air flow 210augmented by auxiliary compressor 208, in accordance with an embodiment.The blocks are provided for illustrative purposes. Variations of theblocks, omission or substitution of various blocks, or additional blocksmay be considered. Method 260 may be performed using various componentsof a gas turbine engine system, including fluid conditioning system 200and auxiliary compressor 208, as described herein.

At block S262, bypass air flow 32 is generated in bypass duct 24 by fan12 that is drivingly coupled to engine core 20 of engine 10.

At block S264, auxiliary compressor 208 drives flow of bleed air flow210, and in some embodiments increases a flow rate of bleed air flow210, through bleed pipe 202 that is in fluid communication with bypassduct 24. In some embodiments, auxiliary compressor 208 is disposedupstream a heat exchanger, such as pre-cooler 206, and thus a locationof driving bleed air flow 210 is upstream a heat exchanger. In someembodiments, auxiliary compressor 208 is disposed downstream a heatexchanger, such as pre-cooler 206, and thus a location of driving bleedair flow 210 is downstream a heat exchanger.

At block S266, pressurized air flow 201A is drawn from engine core 20for cooling by a heat exchanger such as pre-cooler 206, at a heattransfer location to transfer heat between pressurized air flow 201A andbleed air flow 210, and for delivery of cooled pressurized air flow201B, for example, to ECS 40 of the aircraft, or other suitable aircraftair system.

It should be understood that one or more of the blocks may be performedin a different sequence or in an interleaved or iterative manner.

FIGS. 3A and 3B illustrate an example of a gas turbine engine system,including engine 10 and a fluid conditioning system 300.

As shown in FIGS. 3A and 3B, fluid conditioning system 300 includes someof the same structure and components as the architecture of fluidconditioning system 200, including bleed pipe 202 having inlet end 203and defining bleed fluid path 211 through which bleed air flow 210 flowsand is exhausted to bleed exhaust 220, auxiliary compressor 208, as wellas pre-cooler 206, as described herein.

Fluid conditioning system 300 is operable, among other things, tocondition a fluid such as a pre-cooler pressurized air flow 201A′ drawnfrom engine core 20 for cooling by a heat exchanger such as pre-cooler206 using bleed air flow 210 bled from bypass duct 24, and formingcooled pressurized air flow 201B for use in aircraft air systems, suchas an environment control system (ECS) 40, an anti-ice system orsecondary air systems of engine 10.

Fluid conditioning system 300 includes a fluid-driven embodiment ofauxiliary compressor 208 that is driven by a pressurized air flow,described in further detail below.

Fluid conditioning system 300 includes an air pathway or conduitestablishing fluid communication between engine core 20 and pre-cooler206 as well as between engine core 20 and auxiliary compressor 208, fordirecting pressurized air flow 201A drawn from engine core 20 topre-cooler 206 and auxiliary compressor 208.

In some embodiments, fluid communication between engine core 20 andauxiliary compressor 208 is established by an air pathway or conduit,such as fan drive pipe 318 as shown in FIGS. 3C and 3D, branched offfrom an air pathway or conduit between engine core 20 and pre-cooler206. Thus, pressurized air flow 201A is diverted between a pre-coolerpressurized air flow 201A′ to pre-cooler 206 and an auxiliarypressurized air flow 201A″ to auxiliary compressor 208 and auxiliarypressurized air flow 201A″ is a diverted portion of pressurized air flow201A.

In some embodiments, pressurized air flow 201A is drawn from a locationdownstream a low pressure compressor, such as LPC 15A, of engine core20. In some embodiments, pressurized air flow 201A is drawn from alocation downstream a high pressure compressor, such as HPC 15B, of theengine core 20.

In an example, pressurized air flow 201A may be drawn from HPC 15B ofcompressor section 14, such as compressor discharge air pressure (P3).In some embodiments, pressurized air flow 201A may be drawn from othersuitable sections of compressor section 14 or other parts of engine core20, such as between LPC 15A and HPC 15B.

Pressurized air flow 201A may be a relatively high pressure flow, andhigher pressure than bleed air flow 210 within bleed pipe 202.Similarly, pre-cooler pressurized air flow 201A′ and auxiliarypressurized air flow 201A″ may be relatively high pressure flows, andhigher pressure than bleed air flow 210 within bleed pipe 202.

Auxiliary compressor 208, an example fluid propeller, may increase flowrate of bleed air flow 210 through pre-cooler 206 by pushing air throughpre-cooler 206 when disposed upstream pre-cooler 206, or by pulling airthrough pre-cooler 206 when disposed downstream pre-cooler 206.

In an embodiment illustrated in FIG. 3A, auxiliary compressor 208 isdriven by a pressurized air flow, in an example, auxiliary pressurizedair flow 201A″ from engine core 20.

FIG. 3C is a schematic of an example auxiliary compressor 208 insidebleed pipe 202. As shown in FIG. 3C, in some embodiments, auxiliarycompressor 208 includes a bladed rotor 327 having outer radius fanblades 328 for driving bleed air flow 210. Bladed rotor 327 may beconfigured to be driven by impingement of a fluid, such as auxiliarypressurized air flow 201A″ on outer radius fan blades 328 of bladedrotor 327.

To drive auxiliary compressor 208, auxiliary pressurized air flow 201A″may be directed towards outer radius fan blades 328, resulting inrotation of outer radius fan blades 328 and movement of air flow throughbleed fluid path 211 and increasing flow of bleed air flow 210 as acooling flow through pre-cooler 206.

In some embodiments, an exit flow of auxiliary pressurized air flow201A″, from rotation of outer radius fan blades 328, may be mixed withbleed air flow 210. In configurations in which auxiliary compressor 208is upstream pre-cooler 206, the exit flow of auxiliary pressurized airflow 201A″ may be mixed with bleed air flow 210 if flow rates andtemperatures allow. The configuration of auxiliary compressor 208 shownin FIG. 3C may be used upstream or downstream of pre-cooler 206.

In some embodiments, auxiliary compressor 208 may also include a secondbladed rotor, such as an internal shaft turbine 338, that is drivinglycoupled to bladed rotor 327 and outer radius fan blades 328, as shown inFIG. 3D. In some embodiments, bladed rotor 327 and internal shaftturbine 338 are coupled for common rotation. In some embodiments,internal shaft turbine 338 is disposed inside a hub of bladed rotor 327.

Internal shaft turbine 338 may be configured to be driven by impingementof a fluid, such as auxiliary pressurized air flow 201A″ on turbineblades of internal shaft turbine 338.

To drive auxiliary compressor 208, auxiliary pressurized air flow 201A″may be directed towards internal shaft turbine 338, resulting inrotation of internal shaft turbine 338, which in turn rotates outerradius fan blades 328 resulting in movement of air flow through bleedfluid path 211 and increasing flow of bleed air flow 210 as a coolingflow through pre-cooler 206.

In some embodiments, an exit flow of auxiliary pressurized air flow201A″, from rotation of internal shaft turbine 338, may be mixed withbleed air flow 210. In configurations in which auxiliary compressor 208is upstream pre-cooler 206, the exit flow of auxiliary pressurized airflow 201A″ may be mixed with bleed air flow 210 if flow rates andtemperatures allow.

In some embodiments, bladed rotor 327 and internal shaft turbine 338 arefluidically separated to substantially prevent mixing of bleed air flow210 and an exit flow of auxiliary pressurized air flow 201A″. In someembodiments, the exit flow may be captured and exhausted external tobleed air flow 210.

Auxiliary compressor 208 may be operatively disposed upstream ofpre-cooler 206, as shown by way of example in FIG. 3A, or downstream ofpre-cooler 206, as shown by way of example in FIG. 3B.

Conveniently, auxiliary compressor 208 disposed downstream of pre-cooler206 may have the benefit of not further raising the temperature of bleedair flow 210 prior to entry into pre-cooler 206 for cooling pre-coolerpressurized air flow 201A′.

As shown in FIG. 3B, with auxiliary compressor 208 downstream ofpre-cooler 206, bleed air flow 210 travels as a cooling flow throughpre-cooler 206 before reaching auxiliary compressor 208, therebyincreasing the flow rate of air supplied to cool pre-cooler 206, andwhich is then exhausted to bleed exhaust 220, for example, dumped intoan exhaust stream fed into a pylon section of the aircraft and exitedoverboard at a rear of the pylon.

FIG. 3E is a flow diagram of an example method 360 for conditioning afluid, such as pre-cooler pressurized air flow 201A′, using bleed airflow 210 augmented by a fluid-driven configuration of auxiliarycompressor 208, in accordance with an embodiment. The blocks areprovided for illustrative purposes. Variations of the blocks, omissionor substitution of various blocks, or additional blocks may beconsidered. Method 360 may be performed using various components of agas turbine engine system, including fluid conditioning system 300 andauxiliary compressor 208, as described herein.

At block S362, bypass air flow 32 is generated in bypass duct 24 by fan12 that is drivingly coupled to engine core 20 of engine 10.

At block S364, auxiliary pressurized air flow 201A″ is drawn from enginecore 20 to drive auxiliary compressor 208.

At block S366, auxiliary compressor 208 drives flow of bleed air flow210, and in some embodiments increases a flow rate of bleed air flow210, through bleed pipe 202 that is in fluid communication with bypassduct 24. In some embodiments, auxiliary compressor 208 is disposedupstream a heat exchanger, such as pre-cooler 206, and thus a locationof driving bleed air flow 210 is upstream a heat exchanger. In someembodiments, auxiliary compressor 208 is disposed downstream a heatexchanger, such as pre-cooler 206, and thus a location of driving bleedair flow 210 is downstream a heat exchanger.

At block S368, pre-cooler pressurized air flow 201A′ is drawn fromengine core 20 for cooling by a heat exchanger such as pre-cooler 206,at a heat transfer location to transfer heat between pre-coolerpressurized air flow 201A′ and bleed air flow 210, and for delivery ofcooled pressurized air flow 201B, for example, to ECS 40 of theaircraft, or other suitable aircraft air system.

In some embodiments, pre-cooler pressurized air flow 201A′ and auxiliarypressurized air flow 201A″ are both portions of pressurized air flow201A, and are both drawn from a same location of engine core 20.

It should be understood that one or more of the blocks may be performedin a different sequence or in an interleaved or iterative manner.

FIG. 4A is a schematic of a fluid conditioning system 400 having anejector pump 408, in accordance with an embodiment. Fluid conditioningsystem 400 may be part of a gas turbine engine system that also includesengine 10 (not shown in FIG. 4A).

Fluid conditioning system 400 includes some of the same structure andcomponents as the architecture of fluid conditioning system 200,including bleed pipe 202 having inlet end 203 and defining bleed fluidpath 211 through which bleed air flow 210 flows and is exhausted tobleed exhaust 220, as well as pre-cooler 206, as described herein.

In place of auxiliary compressor 208, fluid conditioning system 400 mayinclude ejector pump 408.

Fluid conditioning system 400 is operable, among other things, tocondition a fluid such as pre-cooler pressurized air flow 201A′ drawnfrom engine core 20 for cooling by a heat exchanger such as pre-cooler206 using bleed air flow 210 bled from bypass duct 24, and formingcooled pressurized air flow 201B for use in aircraft air systems, suchas an environment control system (ECS) 40, an anti-ice system orsecondary air systems of engine 10.

Fluid conditioning system 400 includes an air pathway or conduitestablishing fluid communication between engine core 20 and pre-cooler206 as well as ejector pump 408 for directing pressurized air flow 201Adrawn from engine core 20 to pre-cooler 206 and ejector pump 408.

In some embodiments, fluid communication between engine core 20 andejector pump 408 is established by an air pathway or conduit branchedoff from an air pathway or conduit between engine core 20 and pre-cooler206. Thus, pressurized air flow 201A is diverted between a pre-coolerpressurized air flow 201A′ to pre-cooler 206 and an auxiliarypressurized air flow 201A″ to ejector pump 408 and auxiliary pressurizedair flow 201A″ is a diverted portion of pressurized air flow 201A.

In some embodiments, pressurized air flow 201A is drawn from a locationdownstream a low pressure compressor, such as LPC 15A, of engine core20. In some embodiments, pressurized air flow 201A is drawn from alocation downstream a high pressure compressor, such as HPC 15B, of theengine core.

In an example, pressurized air flow 201A may be drawn from HPC 15B ofcompressor section 14, such as compressor discharge air pressure (P3).In some embodiments, pressurized air flow 201A may be drawn from othersuitable sections of compressor section 14 or other parts of engine core20, such as between LPC 15A and HPC 15B.

Pressurized air flow 201A may be a relatively high pressure flow, andhigher pressure than bleed air flow 210 within bleed pipe 202.Similarly, pre-cooler pressurized air flow 201A′ and auxiliarypressurized air flow 201A″ may be relatively high pressure flows, andhigher pressure than bleed air flow 210 within bleed pipe 202.

Fluid conditioning system 400 includes a pneumatic ejector such asejector pump 408, an example fluid propeller configured to drive bleedair flow 210 through pre-cooler 206, to increase pressure differential,and thus air flow rate, across pre-cooler 206.

Ejector pump 408 is driven by a higher-pressure pressurized air flow, inan example, auxiliary pressurized air flow 201A″ from engine core 20, topump lower pressure pump bleed air flow 210.

Ejector pump 408 may include a nozzle that allows motive fluid such asauxiliary pressurized air flow 201A″ to enter a mixing chamber or regioninto which suction fluid such as bleed air flow 210 is also received.The auxiliary pressurized air flow 201A″ may further energize andentrain the bleed air flow 210. The ejector pump 408 may have an outletvia which the mixture of auxiliary pressurized air flow 201A″ and bleedair flow 210 is discharged. The ejector pump 408 may have a diffuserthrough which the mixture of auxiliary pressurized air flow 201A″ andbleed air flow 210 flows prior to being discharged via the outlet.

A relatively small amount of higher pressure air, such as auxiliarypressurized air flow 201A″, may be used to increase the flow rate of theslower, lower pressure air that forms bleed air flow 210, for example,at a ratio of ˜1% higher pressure air to lower pressure air.

Ejector pump 408 generates ejector exhaust flow 418 from auxiliarypressurized air flow 201A″ that, in some embodiments, exhausts to bleedpipe 202.

In some embodiments, a valve (not shown) may be placed on auxiliarypressurized air flow 201A″ line to modulate the flow of auxiliarypressurized air flow 201A″ and thus allow ejector pump 408 to be turnedon or off as desired. The valve may be a ball valve, or other suitablevalve.

FIG. 4A illustrates fluid conditioning system 400 having ejector pump408 operatively disposed downstream of pre-cooler 206, in accordancewith an embodiment. In some embodiments, ejector pump 408 may bedisposed upstream of pre-cooler 206.

Conveniently, ejector pump 408 disposed downstream of pre-cooler 206 mayhave the benefit of not further raising the temperature of bleed airflow 210 prior to entry into pre-cooler 206 for cooling pre-coolerpressurized air flow 201A′.

In some embodiments, a first fluid propeller, such as ejector pump 408,is disposed downstream of a heat exchanger such as pre-cooler 206, and asecond fluid propeller, such as ejector pump 408 or other type, isdisposed upstream of a heat exchanger such as pre-cooler 206.

FIG. 4B is a flow diagram of an example method 460 for conditioning afluid, such as pre-cooler pressurized air flow 201A′, using bleed airflow 210 augmented by ejector pump 408, in accordance with anembodiment. The blocks are provided for illustrative purposes.Variations of the blocks, omission or substitution of various blocks, oradditional blocks may be considered. Method 460 may be performed usingvarious components of a gas turbine engine system, including fluidconditioning system 400 and ejector pump 408, as described herein.

At block S462, bypass air flow 32 is generated in bypass duct 24 by fan12 that is drivingly coupled to engine core 20 of engine 10.

At block S464, auxiliary pressurized air flow 201A″ is drawn from enginecore 20 to drive ejector pump 408.

At block S466, ejector pump 408 drives flow of bleed air flow 210, andin some embodiments increases a flow rate of bleed air flow 210, throughbleed pipe 202 that is in fluid communication with bypass duct 24. Insome embodiments, ejector pump 408 is disposed upstream a heatexchanger, such as pre-cooler 206, and thus a location of driving bleedair flow 210 is upstream a heat exchanger. In some embodiments, ejectorpump 408 is disposed downstream a heat exchanger, such as pre-cooler206, and thus a location of driving bleed air flow 210 is downstream aheat exchanger.

At block S468, pre-cooler pressurized air flow 201A′ is drawn fromengine core 20 for cooling by a heat exchanger such as pre-cooler 206,at a heat transfer location to transfer heat between pre-coolerpressurized air flow 201A′ and bleed air flow 210, and for delivery ofcooled pressurized air flow 201B, for example, to ECS 40 of theaircraft, or other suitable aircraft air system.

In some embodiments, pre-cooler pressurized air flow 201A′ and auxiliarypressurized air flow 201A″ are both portions of pressurized air flow201A, and are both drawn from a same location of engine core 20.

It should be understood that one or more of the blocks may be performedin a different sequence or in an interleaved or iterative manner.

FIG. 5A is a schematic of a fluid conditioning system 500 havingauxiliary compressor 208, in accordance with an embodiment. Fluidconditioning system 500 may be part of a gas turbine engine system thatalso includes engine 10 (not shown in FIG. 5A).

Fluid conditioning system 500 includes some of the same structure andcomponents as the architecture of fluid conditioning system 200,including bleed pipe 202 having inlet end 203 and defining bleed fluidpath 211 through which bleed air flow 210 flows and is exhausted tobleed exhaust 220, auxiliary compressor 208, as well as pre-cooler 206,as described herein.

Fluid conditioning system 500 is operable, among other things, tocondition a fluid such as pressurized air flow 201A drawn from enginecore 20 for cooling by a heat exchanger such as pre-cooler 206 usingbleed air flow 210 bled from bypass duct 24, and forming cooledpressurized air flow 201B for use in aircraft air systems, such as anenvironment control system (ECS) 40, an anti-ice system or secondary airsystems of engine 10.

Fluid conditioning system 500 includes a mechanically-driven embodimentof auxiliary compressor 208 that is drivingly coupled to a driveshaft528, described in further detail below.

Fluid conditioning system 500 includes an air pathway or conduitestablishing fluid communication between engine core 20 and pre-cooler206 for directing pressurized air flow 201A drawn from engine core 20 topre-cooler 206.

In some embodiments, pressurized air flow 201A is drawn from a locationdownstream a low pressure compressor, such as LPC 15A, of engine core20. In some embodiments, pressurized air flow 201A is drawn from alocation downstream a high pressure compressor, such as HPC 15B, of theengine core.

In an example, pressurized air flow 201A may be drawn from HPC 15B ofcompressor section 14, such as compressor discharge air pressure (P3).In some embodiments, pressurized air flow 201A may be drawn from othersuitable sections of compressor section 14 or other parts of engine core20, such as between LPC 15A and HPC 15B.

Pressurized air flow 201A may be a relatively high pressure flow, andhigher pressure than bleed air flow 210 within bleed pipe 202.

In some embodiments, a turbine 518 is operatively disposed inline withpressurized air flow 201A to drive driveshaft 528 that is drivinglycoupled to rotate auxiliary compressor 208, in particular, a fan orturbine of auxiliary compressor 208, to generate movement of air flowthrough bleed fluid path 211, increasing flow rate of bleed air flow 210through pre-cooler 206.

Conveniently, as pressurized air flow 201A passes through turbine 518,and turbine 518 extracts energy from pressurized air flow 201A, thetemperature of pressurized air flow 201A exhausted from turbine 518 maydrop. Thus, a lower temperature flow is introduced to pre-cooler 206,thus may require pre-cooler 206 to do less work to cool pressurized airflow 201A to form cooled pressurized air flow 201B.

In some embodiments, a diverter valve 536 may be disposed upstream ofturbine 518 on pressurized air flow 201A line to modulate the flow ofpressurized air flow 201A and to divert pressurized air flow 201A aroundturbine 518 and thus allow turbine 518 to be turned on or off asdesired.

Diverter valve 536 may be a ball valve, or other suitable valve.

FIG. 5A illustrates fluid conditioning system 500 having auxiliarycompressor 208 operatively disposed downstream of pre-cooler 206, inaccordance with an embodiment. In some embodiments, auxiliary compressor208 may be disposed upstream of pre-cooler 206.

Conveniently, auxiliary compressor 208 disposed downstream of pre-cooler206 may have the benefit of not further raising the temperature of bleedair flow 210 prior to entry into pre-cooler 206 for cooling pressurizedair flow 201A.

FIG. 5B is a flow diagram of an example method 560 for conditioning afluid, such as pressurized air flow 201A, using bleed air flow 210augmented by a mechanically-driven configuration of auxiliary compressor208, in accordance with an embodiment. The blocks are provided forillustrative purposes. Variations of the blocks, omission orsubstitution of various blocks, or additional blocks may be considered.Method 560 may be performed using various components of a gas turbineengine system, including fluid conditioning system 500 and auxiliarycompressor 208, as described herein.

At block S562, bypass air flow 32 is generated in bypass duct 24 by fan12 that is drivingly coupled to engine core 20 of engine 10.

At block S564, pressurized air flow 201A is drawn from engine core 20 todrive turbine 518 which in turn drives driveshaft 528. Driveshaft 528 inturn drives auxiliary compressor 208.

In some embodiments, diverter valve 536 selectively diverts pressurizedair flow 201A around turbine 518.

At block S566, pressurized air flow 201A, for example, exhausted fromturbine 518, is directed to a heat exchanger such as pre-cooler 206 forcooling, at a heat transfer location to transfer heat betweenpressurized air flow 201A and bleed air flow 210, and for delivery ofcooled pressurized air flow 201B, for example, to ECS 40 of theaircraft, or other suitable aircraft air system.

At block S568, auxiliary compressor 208 drives flow of bleed air flow210, and in some embodiments increases a flow rate of bleed air flow210, through bleed pipe 202 that is in fluid communication with bypassduct 24. In some embodiments, auxiliary compressor 208 is disposedupstream a heat exchanger, such as pre-cooler 206, and thus a locationof driving bleed air flow 210 is upstream a heat exchanger. In someembodiments, auxiliary compressor 208 is disposed downstream a heatexchanger, such as pre-cooler 206, and thus a location of driving bleedair flow 210 is downstream a heat exchanger.

It should be understood that one or more of the blocks may be performedin a different sequence or in an interleaved or iterative manner.

FIG. 6A is a schematic of a fluid conditioning system 600 havingauxiliary compressor 208 and ejector pump 408, in accordance with anembodiment. Fluid conditioning system 600 may be part of a gas turbineengine system that also includes engine 10 (not shown in FIG. 6A).

Fluid conditioning system 600 includes some of the same structure andcomponents as the architecture of fluid conditioning system 200 andfluid conditioning system 400, including bleed pipe 202 having inlet end203 and defining bleed fluid path 211 through which bleed air flow 210flows and is exhausted to bleed exhaust 220, auxiliary compressor 208,ejector pump 408, as well as pre-cooler 206, as described herein.

Fluid conditioning system 600 is operable, among other things, tocondition a fluid such as pre-cooler pressurized air flow 201A′ drawnfrom engine core 20 for cooling by a heat exchanger such as pre-cooler206 using bleed air flow 210 bled from bypass duct 24, and formingcooled pressurized air flow 201B for use in aircraft air systems, suchas an environment control system (ECS) 40, an anti-ice system orsecondary air systems of engine 10.

Fluid conditioning system 600 includes an air pathway or conduitestablishing fluid communication between engine core 20 and pre-cooler206 as well as between engine core 20 and auxiliary compressor 208, fordirecting pressurized air flow 201A drawn from engine core 20 topre-cooler 206 and auxiliary compressor 208.

In some embodiments, fluid communication between engine core 20 andauxiliary compressor 208 is established by an air pathway or conduitbranched off from an air pathway or conduit between engine core 20 andpre-cooler 206. Thus, pressurized air flow 201A is diverted between apre-cooler pressurized air flow 201A′ to pre-cooler 206 and an auxiliarypressurized air flow 201A″ to auxiliary compressor 208, and auxiliarypressurized air flow 201A″ is a diverted portion of pressurized air flow201A.

In some embodiments, pressurized air flow 201A is drawn from a locationdownstream a low pressure compressor, such as LPC 15A, of engine core20. In some embodiments, pressurized air flow 201A is drawn from alocation downstream a high pressure compressor, such as HPC 15B, of theengine core.

In an example, pressurized air flow 201A may be drawn from HPC 15B ofcompressor section 14, such as compressor discharge air pressure (P3).In some embodiments, pressurized air flow 201A may be drawn from othersuitable sections of compressor section 14 or other parts of engine core20, such as between LPC 15A and HPC 15B.

Pressurized air flow 201A may be a relatively high pressure flow, andhigher pressure than bleed air flow 210 within bleed pipe 202.Similarly, pre-cooler pressurized air flow 201A′ and auxiliarypressurized air flow 201A″ may be relatively high pressure flows, andhigher pressure than bleed air flow 210 within bleed pipe 202.

Auxiliary compressor 208 may increase flow rate of bleed air flow 210through pre-cooler 206 by increasing the pressure gradient acrosspre-cooler 206, as described herein.

Auxiliary compressor 208 is driven by a pressurized air flow, in anexample, auxiliary pressurized air flow 201A″ from engine core 20.

In some embodiments, as illustrated in FIG. 3D, auxiliary compressor 208is driven by auxiliary pressurized air flow 201A″ directed towardsinternal shaft turbine 338, rotatably coupled to outer radius fan blades328, to rotate outer radius fan blades 328, as described above, toincrease the flow rate of bleed air flow 210 as a cooling flow throughpre-cooler 206. Auxiliary compressor 208 of FIG. 6A may have theconfiguration shown in FIG. 3D.

As shown in FIG. 6A, in some embodiments, exit flow from auxiliarycompressor 208 may be captured (for example, contained in an exhaustpipe) as compressor exhaust flow 201C and exhausted external to bleedair flow 210.

In some embodiments, auxiliary compressor 208 includes internal shaftturbine 338, captured compressor exhaust flow 201C may be exit flowgenerated by rotation of internal shaft turbine 338.

While auxiliary compressor 208 is shown in FIG. 6A as fluid-driven, insome embodiments it will be appreciated that auxiliary compressor 208may be mechanically-driven by other means, for example, by a drive shaftsuch as driveshaft 528, or electrically driven, as described herein.

Fluid conditioning system 600 includes a pneumatic ejector, such asejector pump 408, to increase pressure differential, and thus air flowrate, across pre-cooler 206.

Ejector pump 408 is driven by a higher-pressure pressurized air flow, inan example, compressor exhaust flow 201C from auxiliary compressor 208,to pump lower pressure bleed air flow 210. In some embodiments,auxiliary compressor 208 and ejector pump 408 may be operatively coupledto be driven by a common flow of pressurized air, such as pressurizedair flow 201A, received from compressor section 14 of engine 10.

Ejector pump 408 generates ejector exhaust flow 418 from auxiliarypressurized air flow 201A″ that exhausts to bleed pipe 202.

In the embodiment illustrated in FIG. 6A, auxiliary compressor 208 isdisposed upstream of pre-cooler 206 and ejector pump 408 is disposeddownstream of pre-cooler 206. Other configurations are alsocontemplated. In some embodiments, ejector pump 408 may be disposedupstream of pre-cooler 206 and auxiliary compressor 208 disposeddownstream of pre-cooler 206. It will be appreciated that in someembodiments, both auxiliary compressor 208 and ejector pump 408 may bedisposed upstream of pre-cooler 206 and in some embodiments, bothauxiliary compressor 208 and ejector pump 408 may be disposed downstreamof pre-cooler 206.

Thus, a location of driving bleed air flow 210 may be upstream a heatexchanger, such as pre-cooler 206, downstream a heat exchanger, or both.

Conveniently, one or both of auxiliary compressor 208 and ejector pump408 disposed downstream of pre-cooler 206 may have the benefit of notfurther raising the temperature of bleed air flow 210 prior to passingthrough pre-cooler 206 for cooling pre-cooler pressurized air flow201A′.

Auxiliary compressor 208 and ejector pump 408 each disposed on opposingstream-sides (upstream and downstream) of pre-cooler 206 may allow forboth a push and a pull effect to be applied to bleed air flow 210, thecooling flow for pre-cooler 206, and may further augment the coolingflow rate should the available flow or pressure from bleed air flow 210be too low, for example, if either auxiliary compressor 208 or ejectorpump 408 alone would not be sufficient to augment the cooling flow ofbleed air flow 210.

FIG. 6B is a flow diagram of an example method 660 for conditioning afluid, such as pre-cooler pressurized air flow 201A′, using bleed airflow 210 augmented by auxiliary compressor 208 and ejector pump 408, inaccordance with an embodiment. The blocks are provided for illustrativepurposes. Variations of the blocks, omission or substitution of variousblocks, or additional blocks may be considered. Method 660 may beperformed using various components of a gas turbine engine system,including fluid conditioning system 600, auxiliary compressor 208 andejector pump 408, as described herein.

At block S661, bypass air flow 32 is generated in bypass duct 24 by fan12 that is drivingly coupled to engine core 20 of engine 10.

At block S662, auxiliary pressurized air flow 201A″ is drawn from enginecore 20 to drive auxiliary compressor 208.

At block S663, auxiliary compressor 208 drives flow of bleed air flow210, and in some embodiments increases a flow rate of bleed air flow210, through bleed pipe 202 that is in fluid communication with bypassduct 24. In some embodiments, auxiliary compressor 208 is upstream aheat exchanger, such as pre-cooler 206 that is in contact with bleed airflow 210 which operates as a cooling flow for pre-cooler 206. In someembodiments, auxiliary compressor 208 is downstream a heat exchanger,such as pre-cooler 206.

At block S664, compressor exhaust flow 201C is directed from auxiliarycompressor 208 to drive ejector pump 408.

At block S665, ejector pump 408 drives flow of bleed air flow 210, andin some embodiments increases a flow rate of bleed air flow 210, throughbleed pipe 202 that is in fluid communication with bypass duct 24. Insome embodiments, ejector pump 408 is upstream a heat exchanger, such aspre-cooler 206 that is in contact with bleed air flow 210 which operatesas a cooling flow for pre-cooler 206. In some embodiments, ejector pump408 is downstream a heat exchanger, such as pre-cooler 206.

At block S666, pre-cooler pressurized air flow 201A′ is drawn fromengine core 20 for cooling by a heat exchanger such as pre-cooler 206,at a heat transfer location to transfer heat between pre-coolerpressurized air flow 201A′ and bleed air flow 210, and for delivery ofcooled pressurized air flow 201B, for example, to ECS 40 of theaircraft, or other suitable aircraft air system.

In some embodiments, pre-cooler pressurized air flow 201A′ and auxiliarypressurized air flow 201A″ are both portions of pressurized air flow201A, and are both drawn from a same location of engine core 20.

It should be understood that one or more of the blocks may be performedin a different sequence or in an interleaved or iterative manner.

In some embodiments, fluid conditioning system 200, fluid conditioningsystem 300, fluid conditioning system 400, fluid conditioning system500, and fluid conditioning system 600 may each include a controller 60in communication with an aircraft air system, such as ECS 40, andoperatively coupled to a fluid propeller, such as auxiliary compressor208 and/or ejector pump 408, and configured to selectively activate thefluid propeller when an activation condition is met. Such activationconditions may occur when additional cooling air flow is needed forpre-cooler 206, for example, a high air demand operating condition of anaircraft air system such as ECS 40. A high air demand operatingcondition may occur, in an example, with the engine operating at arelatively low power with high demands of an anti-ice system whilecruising at 15,000-20,000 feet in a holding condition. Similarly, afluid propeller, such as auxiliary compressor 208 and/or ejector pump408, may be selectively deactivated at a low demand operating condition.Pressure/flow augmentation provided by an auxiliary compressor and/orejector pump can be based on a demand by ECS 40 and/or an altitude ofthe aircraft (e.g., as reflected by a pressure inside of bypass duct 24)which could be controlled by controller 60 according to a suitableschedule.

It should be understood that various components of fluid conditioningsystem 200, fluid conditioning system 300, fluid conditioning system400, fluid conditioning system 500, and fluid conditioning system 600may be used interchangeably in each system.

Of course, the above described embodiments are intended to beillustrative only and in no way limiting. The described embodiments aresusceptible to many modifications of form, arrangement of parts, detailsand order of operation. The disclosure is intended to encompass all suchmodification within its scope, as defined by the claims.

What is claimed is:
 1. A system for conditioning a fluid using bleed airfrom a bypass duct of a turbofan engine, the system comprising: a heatexchanger configured to facilitate heat transfer between a flow of bleedair from the bypass duct of the turbofan engine and the fluid; and afluid propeller configured to drive the bleed air through the heatexchanger, the fluid propeller disposed downstream of the heatexchanger.
 2. The system of claim 1, wherein the fluid is pressurizedair received from a compressor section of the turbofan engine.
 3. Thesystem of claim 1, wherein the fluid propeller is driven by electricityfrom an electric generator driven by the turbofan engine.
 4. The systemof claim 1, wherein the fluid propeller is drivingly coupled to anaccessory gearbox of the turbofan engine.
 5. The system of claim 1,comprising a controller operatively coupled to the fluid propeller andconfigured to selectively activate the fluid propeller at a high demandoperating condition and deactivate the fluid propeller at a low demandoperating condition.
 6. The system of claim 1, wherein the fluidpropeller is a first fluid propeller and the system comprises a secondfluid propeller configured to drive the bleed air through the heatexchanger, the second fluid propeller disposed upstream of the heatexchanger.
 7. A system for conditioning supply air for an environmentalcontrol system of an aircraft, the system comprising: a turbofan gasturbine engine having a bypass duct; a heat exchanger configured tofacilitate heat transfer between a flow of bleed air from the bypassduct and the supply air; and a fluid propeller configured to drive thebleed air through the heat exchanger, the fluid propeller disposeddownstream of the heat exchanger.
 8. The system of claim 7, wherein thesupply air is pressurized air received from a compressor section of theturbofan gas turbine engine.
 9. The system of claim 7, wherein the fluidpropeller is driven by electricity from an electric generator driven bythe turbofan gas turbine engine.
 10. The system of claim 7, wherein thefluid propeller is drivingly coupled to an accessory gearbox of theturbofan gas turbine engine.
 11. The system of claim 7, comprising acontroller operatively coupled to the fluid propeller and configured toselectively activate the fluid propeller at a high demand operatingcondition and deactivate the fluid propeller at a low demand operatingcondition.
 12. The system of claim 7, wherein the fluid propeller is afirst fluid propeller and the system comprises a second fluid propellerconfigured to drive the bleed air through the heat exchanger, the secondfluid propeller disposed upstream of the heat exchanger.
 13. A methodfor conditioning a fluid using a flow of bleed air from a bypass duct ofa turbofan engine, the method comprising: at a heat transfer location,transferring heat between the fluid and the flow of bleed air from thebypass duct of the turbofan engine; and driving the flow of bleed airthrough the heat transfer location, a location of the driving beingdownstream of the heat transfer location.
 14. The method of claim 13,wherein the fluid is pressurized air received from a compressor sectionof the turbofan engine.
 15. The method of claim 13, wherein the drivingof the flow of bleed air driving a fluid propeller using electricityfrom an electric generator driven by the turbofan engine.
 16. The methodof claim 13, wherein the driving of the flow of bleed air includesdriving a fluid propeller using an accessory gearbox of the turbofanengine.
 17. The method of claim 13, wherein the location of the drivingbeing a first location of the driving and the method comprises a secondlocation of the driving upstream of the heat transfer location.